Optical data transceiver modules convert optical signals received via an optical fiber into electrical signals, and convert electrical signals into optical signals for transmission via an optical fiber. In the transmitter portion of a transceiver module, an opto-electronic light source such as a laser performs the electrical-to-optical signal conversion. In the receiver portion of the transceiver module, an opto-electronic light detector such as a photodiode performs the optical-to-electrical signal conversion. A transceiver module commonly also includes optical elements, such as lenses, as well as electrical circuitry such as drivers and receivers. A transceiver module also includes one or more fiber ports to which an optical fiber cable is connected. The light source, light detector, optical elements and electrical circuitry are mounted within a module housing. The one or more fiber ports are located on the module housing.
Various transceiver module configurations are known. One type of transceiver module configuration is known as Small Form Factor Pluggable (SFP). Such SFP transceiver modules include an elongated housing having a substantially rectangular cross-sectional shape. A forward end of the housing is connectable to an optical fiber cable. A rearward end of the housing has an array of electrical contacts that can be plugged into a mating connector when the rearward end is inserted or plugged into a slot of a network switch or other device. An SFP transceiver module having four parallel transmit channels and four parallel receive channels is commonly referred to as Quad SFP or QSFP.
In an SFP transceiver module, the light source and light detector can be mounted on a printed circuit board (PCB) with their optical axes normal to the plane of the PCB. As these device optical axes are perpendicular to the ends of the optical fibers at the forward end of the module housing, there is a need to redirect or “turn” the signals 90 degrees between the fibers and the device optical axes. In an SFP transceiver having only a single channel, the optical elements commonly include one or more reflective surfaces that turn the signals in the optical domain. However, in a QSFP or other parallel optical transceiver module, a 90-degree flex circuit is commonly employed to turn the signals in the electrical domain because turning the signals in the optical domain can present obstacles to achieving good optical alignment.
Achieving and maintaining good optical alignment among multiple parallel opto-electronic devices, lenses, reflective surfaces, and optical fibers can present problems. It would be desirable to provide a parallel optical data transceiver module that promotes good optical alignment among such elements.